This WOWed! me the first time I read it (from Wiseman’s 59 Seconds):
Then there is the infamous ‘Yale Goal Study’. According to some writers, in 1953 a team of researchers interviewed Yale’s graduating seniors, asking them whether they had written down the specific goals that they wanted to achieve in life. Twenty years later the researchers tracked down the same cohort and foudn that the 3 per cent of people who had specific goals all those years before had accumulated more personal wealth than the other 97 percent of their classmates combined. It is a great story, and frequently cited in self-help books and seminars to illustrate the power of goal-setting. There is just one small problem – as far as anyone can tell the experiment never actually took place. In 2007, writer Lawrence Tabak from the magazine Fast Company attempted to track down the study, contacting several writers who had cited it, the secretary of the Yale Class of 1953, and other researchers who had attempted to discover whether the study had actually happened. No one could produce any evidence that it had ever been conducted, causing Tabak to conclude that it was almost certainly nothing more than an urban myth. For years, self-help gurus had been happy to describe a study without checking their facts.
Here’s Tabak’s original article: http://www.fastcompany.com/magazine/06/cdu.html